Ignition timing control means for internal-combustion engines



June 5, 1945.

M. MALLORY IGNITION TIMING CONTROL MEANS FOR INTERNAL-COMBUSTIONENGINESFiled Nov. 19, 1943 7 6 5 4. 3 2 95 6 F W2 5 E anuo P Y 0 1T 0 M M R 500loco v INVENTOR.

Mar/0r? Ma/lary Patented June 5, 1945 UNITED STATES PATENT OFFICEIGNITION TIMING CONTROL MEANS FOR INTERNAL-COMBUSTION ENGINES MarionMallory, Detroit, Mich. Application November 19, 1943, Serial No.510,853

2 Claims.

This invention relates to ignition timing control means for internalcombustion engines.

In my prior Patent 2,268,490 I have disclosed an ignition timer for aninternal combustion engine which is controlled by the pressures in theintake passageway of the engine. I have found that in many instances thepart throttle suction-or vacuum is so high that the spark is too muchadvanced on part throttle. In many cases the part throttle suction isconsiderably higher than the intake passageway suction created by theventuri at high speeds and with the throttle wide open. The suction inthe intake passageway also runs very high in the event the air cleanerbecomes plugged and therefore the spark is too much advanced.

It is the object of this invention to produce a pressure timed ignitionsystem which prevents the spark from being too far advanced on partthrottle and which will efliciently control the advancing and retardingof the spark under all operating conditions. This object is achieved byincorporating a pressure relief valve in the passagewa'y between thesuction operated diaphragm and the intake passageway.

Fig. 1 is a sectional view showing my ignition timing control means forinternal combustion engmes.

Fig. 2 is a graph showing the intake passageway vacuum at various enginespeeds and at part and wide open throttle.

Referring more particularly to the drawing there is shown a, carburetorprovided with a, passageway l including a venturi 2 and the usualbutterfly throttle valve 3 mounted on shaft 4 which is swung opened andclosed by crank 5 and rod 6. The air inlet end of the carburetor isdesignated l and the fuel mixture outlet 8 leading to the engine.

The timing mechanism is conventional and as shown consists of the usualrotatable cam 9 which operates the electrical circuit breaker H). Thecircuit breaker I is mounted on the plate II which can be rotatedclockwise to advance the spark and counterclockwise to retard the spark.A suction device I2 is utilized for advancing and retarding the spark.The suction device comprises a flexible diaphragm I3 backed up by acompression coil spring 14.. The diaphragm I3 is mounted in the housingl which is connected to the carburetor by conduit 16. The diaphragm isconnected to plate I I by connecting rod l1, one end of which ispivotally connected as at l8 to the plate II and the other end of whichis fixed to the diaphragm. The wall I 9 of the housing is perforated sothat the diaphragm is subjected on the outside to atmospheric pressure;whereas, on the inside of the housing IS, the diaphragm is subjectedthrough line 16 to the booster venturi 2 and to orifice 20 locatedbetween the throttle and venturi 2.

Conduit l 6 is connected in parallel by passageways 2| and 22 to orifice23 in the venturi 2 and orifice 20 respectively.

Referring to Fig.2 the Venturi suction at wide open throttle is shown bythe line A. At an engine speed of 3000 R. P. M. the Venturi suction isapproximately five inches of mercury. The part throttl suction is shownby the line B. The part throttle suction at high engine speeds and underother conditions might go up to ten or more inches of mercury whichwould be too much spark advance at part throttle. In my system I havefound that the part throttle vacuum should not run much higher than theVenturi vacuum at high engine speeds. Therefore, line I6 is providedwith an air bleed to atmosphere comprising conduit 25 communicating withconduit "5 and provided with an orifice 26 to atmosphere. Orifice 26 iscontrolled by ball check 21 held against its seat by compression spring28. The strength of spring 28 is chosen or regulated so that if the partthrottle vacuum impressed upon the suction device l2 through conduit I6is too high, valve 21 will open and bleed the suction device toatmosphere sufliciently to bring the vacuum acting upon diaphragm l3down to, or in the neighborhood of, the vacuum created by the venturi 2at high engine speeds.

Orifice 20 is positioned so that whenever throttle valve 3 is openedslightly beyond idle position orifice 20 will be subjected to manifoldsuction. The full manifold suction is not impressed upon the suctiondevice because it is bled down through orifice 23.

The operation of my ignition system is the same as described in myPatent 2,268,490, except that air bleed valve 21 operates whenever thevacuum in conduit l6 reaches or slightly exceeds a vacuum equal to thatcreated in conduit I6 by venturi 2 at wide open throttle and high enginespeeds, such,. for example, 3000 R. P. M. Thus, this air bleed inconduit l6 definitely controls the vacuum impressed on suction diaphragmIE8 at part open throttle so that the spark will be advanced to theright degree at part open throttle.

I claim:

1. In an internal combustion engine having an intake passagewayincluding a venturi and a throttle valve in said intake passageway onthe discharge side of said venturi, the combination of an ignitiontiming mechanism adapted for operation to advance and retard the spark,suction responsive means connected to said timing mechanism foroperating the same, a conduit connecting said suction responsive meansinto the venturi for applying suction to the suction device from theventuri, an orifice in the intake passageway positioned on theatmosphere side of the throttle valve when in idle position and on thedischarge side of the throttle valve in partly open position, a secondconduit for connecting the suction device to said orifice for applyingsuction to the suction device from the discharge side of said throttlevalve in partly opened position, and an air bleed to atmosphere for saidsuction device arranged to open at a predetermined suction to bleed downthe suction impressed upon said suction responsive means to a suctionapproximating that impressed upon the suction device by the venturi atwide open throttle and high engine speed.

2. In an internal combustion engine having an intake passagewayincluding a venturi, a throttle valve on the discharge side of saidventuri, an

asvmee ignition timing mechanism, suction responsive means connected tosaid timing mechanism for advancing and retarding the spark, a conduitconnecting the suction device into the venturi whereby the ignitiontiming mechanism is controlled principally by the vacuum'created by theventuri at wide open throttle and higher engine speeds, an orifice inthe intake passageway positioned on the atmosphere side of the throttlevalve when in idle position and on the discharge side of the throttlevalve in partly open position, another conduit connecting said orificeto the suction device for applying the suction on the discharge side ofthe throttle valve to the suction device whereby at part throttle thesuction device is controlled principally by the manifold vacuum bleddown through the conduit connected into the venturi, and air bleed meanscon-' nected to said suction device arranged to bleed the suction deviceto atmosphere whenever the intake passageway suction on the dischargeside of the throttle valve exceeds a predetermined value whereby anover-spark advance under the operating conditions is prevented.

, MARION MALLORY.

